Statins and Anti-Stroke Drug Combinations May Increase Bleeding Risk

Highlights

Dabigatran is an oral anticoagulant prescribed in atrial fibrillation (AF) patients to reduce risk of stroke, with similar efficacy to warfarin, another popular oral anticoagulant.
Dabigatran is preferred over warfarin since it carries lesser risk of major life threatening bleeds when compared to warfarin.
Simvastatin and Lovastatin are two commonly used ‘statins’ to reduce levels of LDL or bad cholesterol and triglycerides.
Recent studies have shown that the risk of hemorrhage is much higher if either Simvastatin or Lovastatin, is given to patients taking dabigatran.

Two commonly prescribed ‘statins’, Simvastatin and Lovastatin , used to lower levels of LDL cholesterol and triglycerides for prevention of heart disease, have been shown to cause increased incidence of bleeding when given to patients on dabigatran , a drug prescribed to prevent stroke in atrial fibrillation patients, according to a recent study in Ontario, Canada.

Aim of the Study
Atrial fibrillation and high lipid levels are both independently associated with a higher risk of stroke and heart disease, and can occur in the same patient. Consequently dabigatran and statins might be prescribed together for treatment.

Statins and Heart Disease Drug Interaction Management: New Statement Guidance
A scientific statement from the American Heart Association provides guidance for managing statins and heart disease drug interactions.

‘Alternative statins like atorvastatin should be considered for patients on dabigatran to reduce bleeding risk.’

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The study, conducted in Canada aimed to determine any adverse drug interactions that could occur between statins (lipid lowering agents) and dabigatran, a direct acting anticoagulant, prescribed in patients with AF.

Interestingly, studies conducted earlier have detected significant drug-drug interactions between warfarin (another oral anticoagulant) and statins, potentiating the anticoagulant effect of warfarin.

Details and Findings of the Study

Dabigatran

This medication is an anticoagulant (blood thinner), prescribed for preventing strokes or serious blood clots in risky patients.

Two separate studies were conducted on the residents of Ontario, aged 65 years and above who were started on dabigatran between 2012 and 2014, and involved a total of 45,991 patients. The findings of the study were as follows

397 patients suffered a stroke and 1117 persons had a major hemorrhage.
The risk of bleeding increased by over 40 percent in patients who also took Simvastatin or Lovastatin, in comparison to those who were on other statins.
The stroke risk of both Simvastatin and Lovastatin was similar in patients taking dabigatran.

"We found no difference in the risk of stroke in patients receiving dabigatran who were prescribed lovastatin or simvastatin versus other statins," said Dr. Tony Antoniou, a pharmacist at St. Michael's Hospital and researcher in its La Ka Shing Knowledge Institute and an adjunct scientist at the Institute for Clinical Evaluative Sciences.

Possible Mechanism of Interaction Between Statins and Dabigatran

Simvastatin and Lovastatin are thought to enhance dabigatran absorption by the body, causing increased blood levels, potentiating its anticoagulant effect and increasing risk of hemorrhage. This effect is not observed with other statins such as Atorvastatin .

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Babies that are exposed to excessive stress hormones in the womb are often born underweight and have a greater risk of heart disease in later life.

Lessons from the Study

The findings of the study indicate that a potentially harmful and clinically significant drug interaction occurs between dabigatran and Simvastatin/Lovastatin. In patients with atrial fibrillation on dabigatran, alternative statins such as Atorvastatin should be considered instead of Simvastatin or Lovastatin.

Source-Medindia